The present invention relates to a collapsible keyboard, especially to a collapsible key board for compact electronic devices such as a PDA (personal digital assistant).
The current trend of electronic products is to provide portability for the user. Therefore, the PDA and cellular phones are prevailing, and user interfaces for the portable electronic products, such as keyboards, are also under extensive development.
The design goals of the keyboards for portable electronic products is compact size and preserving good ergonomics and function.
The size of the keyboard can be reduced by decreasing the size of each keyswitch on the keyboard. Alternatively, the separation between adjacent keyswitches can also be reduced for further decreasing the size of the keyboard. However, the keyboard with over crowded arrangement of keyswitches may cause frequent typewriting errors.
The foldable keyboard is another kind of keyboard for providing portability. However, the reduction in size still has limits.
FIG. 1 shows a prior art keyboard with variable volume. The keyboard has a plurality of keyswitches 1a. A sidewall 10a is arranged on a lateral side of one keyswitch 1a and attached to an inner surface of a supporting wall 20a of a base 2a, whereby the keyswitch 1a can be slid in a vertical direction. The keyswitch 1a further has a restoring spring ha with a bump 12a on a topside thereof. The bump 12a is in contact with a top inner surface of the keyswitch 1a to boost the keyswitch 1a for operation. The keyswitch 1a further has a cylindrical shaft 14a below the spring ha and having serrations 13a on an outer circumference thereof. The cylindrical shaft 14a is pivotally arranged on a retaining case 21 a of the base 2a. Moreover, a driving plate 15a is engaged with the serrations 13a of the cylindrical shaft 14a and connected to another keyswitch 1a. To shrink the keyboard, the driving plate 15a is pushed by an adjacent keyswitch 1a and rotates the cylindrical shaft 14 through the serrations 13a. As shown in FIG. 2, the bump 12a separates from the top inner surface of the keyswitch 1a and then the keyswitch 1a falls by the weight per se.
In the above-mentioned keyboard, the keyswitch 1a falls to reduce the volume of the keyboard. However, the keyswitch 1a should have sufficient height to accommodate the cylindrical shaft 14a and the driving plate 15a. The effect of volume reduction is limited.
Moreover, the keyswitch 1 has a complicated structure and the assembling thereof is cumbersome.
It is the object of the present invention to provide a collapsible keyboard with keyswitches having standard separation during operation and having reduced separation after operation.
To achieve the above object, the present invention provides a collapsible keyboard having at least one keyboard module. The keyboard module has a plurality of keyswitches arranged in an array pattern. At least one membrane circuit is provided to connect the plurality of keyswitches. When the keyboard is in an operation state, each keyswitch has a predetermined separation with an adjacent keyswitch, and the separation is the same as that in a standard keyboard. To shrink the keyboard, the plurality of keyswitches can be arranged in a collapsed state to reduce the transverse size of the keyboard, the lengthwise size of the keyboard, or both sizes. The various objects and advantages of the present invention will be more readily separation is the same as that in a standard keyboard. To shrink the keyboard, the plurality of keyswitches can be arranged in a collapsed state to reduce the transverse size of the keyboard, the lengthwise size of the keyboard, or both sizes. The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawings, in which: